Most anyone can plant a seed or plant and get it to grow in just about any kind of soil. After more than 40 years of vegetable gardening, the last twenty organic gardening, the most important thing I have learned is that the pH of soil is by far the most critical. The optimal pH for growing most vegetables is between 6.0 and 7.2.
What does pH mean? It actually stands for the Power of Hydrogen or H + ions. The scale for pH is measured from 0 – 14 and as the number of hydrogen ions increases the soil pH decreases. Zero is very acidic and something that has a 0.0 pH is hydrochloric acid. Fourteen is very alkaline and sodium hydroxide, also called lye, measures a pH of 14.0. Neutral is considered 7.0 and pure water is an example of something that has a neutral pH.
Soil nutrients are broken up into what is called Macro and Micro Nutrients. Macro Nutrients are Nitrogen (N), Potassium (P), Phosphorus (K), Sulfur (S), Calcium (Ca), and Magnesium (Mg). You will see the top three Macro Nutrients, NPK, listed on every bag of fertilizer on the market. Macro nutrients are Iron (Fe), Manganese (Mn), Boron (B), Copper (Cu), and Zinc (Zn)
You may hear many so-called experts talk first about the nitrogen in soil, phosphorus in soil, or the potassium in soil. This is like someone trying to sell you a brand new beautiful car without an engine. The pH of soil is the engine! It is very important to understand that you could have high levels of every Macro & Micro Nutrient in your soils, but they are only available to plants if the pH is in the right range.
This pH scale from 0-14 is on a base ten scale. This means a substance that has a pH of 4 is 10 times (10 x 1) more acidic than a substance that has a pH of 5, 100 times (10 x 10) more acidic than a pH of 6, and 1000 times (10 x 10 x 10) more acidic than a pH of 7. Determining the pH of soil in your garden is easy.
Do not waste your money on the soil test kits you can buy from the big box stores. They are very inaccurate and unreliable. Your money, and especially your time, are best spent having a professional soils lab do the testing. For years I was relying on a simple test kit I purchased that had powered capsules you mixed with soil & water along with a color chart which proved to be VERY inaccurate.
The pH of soil determines how well, or not, a plant can absorb available nutrients. Think of pH as the lifeblood, or better yet the vanes, of your garden. This does not mean you will not be able to grown vegetables if the pH is outside this range, but for maximum results with most every plant in organic vegetable gardening soil pH is the key
When your pH of soil drops below 6.0 the ability for most vegetable plants to absorb nitrogen, sulfur, calcium, and magnesium drops off quickly. When the pH is above 7.2 most vegetable plants start having problems absorbing iron, manganese, and boron. If your pH is between 7.5 and 8.4 available phosphorus to plants is less than half what it is with a pH between 6 – 7.2. Any pH over 7.5 has another challenge with copper and zinc becoming more and more unavailable to plants as the pH climbs.
If you thought you had a soil pH between 6 – 7.2 and it really was above 7.5 your garden plants can exhibit an iron or phosphorus deficiency. Adding all the phosphorus and iron in the world will not change how your plants grow unless the pH of soil is adjusted. Most likely why garden centers do not want to talk to you about the pH is either they do not know how to help you change it or they already know that it is sometimes very difficult to change.
Depending on where you live in the world you will have different challenges with pH. In the majority of humid regions of the world pH of soil tends to be more acidic while in the vast dry regions the ph is more alkaline. In dry regions the amounts of natural Macro & Micro Nutrients, excluding Nitrogen in Soil, is usually high. This is due to the low amount of annual rainfall not washing away these minerals over time. The opposite is true in most humid regions of the world.
A list of For garden That vegetables vegetables grow best in any Particular pH range you can lands check out this chart " by Ideal Soil pH" . As you can see some vegetables have the ability to grow very well in a pH of Soil in a much wider range such as Watercress that loves the pH to be between 5.0 – 8.0. On the other hand if you want to grow potatoes they grow best with a pH between 4.5 – 6.0.
I speak all over the country on Organic Gardening 101 and on advanced gardening techniques and the one thing that always amazes me is the lack of Quality advise there is out in this market, especially when it comes to soils. Do yourself a big favor and get a professional soils test performed on your garden soil. Once you know your pH of soil you can start tailoring what you grow to your existing soils while working to adjusting your pH over time. The actual job of adjusting the pH can be challenging. For more information on adjusting the pH of your soils please contact The Bird Man.